1. Field of the Invention
The present invention relates to a transfer apparatus for transferring a target object, such as a semiconductor wafer, in a processing system, such as a semiconductor processing system; a processing system employing the transfer apparatus; and a method for controlling the transfer apparatus. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target object, such as a semiconductor wafer or a glass substrate used for an LCD (Liquid Crystal Display) or FPD (Flat Panel Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target object.
2. Description of the Related Art
In the process of manufacturing semiconductor devices, a semiconductor wafer is subjected to various semiconductor processes, such as film formation (e.g., CVD (Chemical Vapor Deposition)), etching, sputtering, oxidation, diffusion, and so forth. In these processes, owing to the demands of increased miniaturization and integration of semiconductor devices, the throughput and yield involving these processes need to be increased. In light of this, there is a semiconductor processing system of the so-called cluster tool type (i.e., multi-chamber type), which has a plurality of process chambers for performing the same process, or a plurality of process chambers for performing different processes, connected to a common transfer chamber. With this system, various steps can be performed in series, without exposing a wafer to air.
Processing systems of the cluster tool type include a common transfer chamber formed of a polygonal (e.g., hexagonal) casing, and a plurality of process chambers and load-lock chambers respectively connected to the side surfaces of the common transfer chamber. In such processing systems, the common transfer chamber is provided with a transfer apparatus disposed near the center thereof and having an articulated transfer arm, which is extendable/retractable and swingable. The transfer arm can face each of the chambers including the process chambers by rotation of the transfer apparatus. Accordingly, a wafer can be transferred to and from any one of the chambers including the process chambers (i.e., they are accessible) by rotation of the transfer apparatus (e.g., Jpn. Pat. Appln. KOKAI Publication No. 8-46013 (Patent Document 1).
In this transfer apparatus, when the transfer arm is swung along with a wafer supported thereon, it is necessary to maintain the position of the wafer, although a swing motion is preferably performed at a high speed. For this reason, for example, an acceleration to be applied to a wafer on the transfer arm is considered, and the transfer arm is controlled during the swing to set the acceleration to be less than a permissible limit (e.g., a permissible maximum acceleration or permissible maximum acceleration change rate).
Further, in recent years, owing to the demands of increased miniaturization and integration of semiconductor devices, the number of steps has been increased in the process of manufacturing semiconductor devices. Accordingly, the number of process chambers connected to a common transfer chamber is preferably increased to improve the process efficiency. In this respect, there is known a processing system of such a type that includes two or more processing sections each having a common transfer chamber with a transfer apparatus disposed therein, and a plurality of process chambers respectively connected to the side surfaces of the common transfer chamber. In this processing system, a wafer can be transferred to and from any one of the process chambers of the processing sections (i.e., they are accessible) by rotation of the respective transfer apparatuses.